There has of course long been a significant interest in developing improved water-proof or non-rewet leathers and/or better treatment methods for producing such leathers. In particular there has been an increasing desire to develop an aqueous system for producing a non-rewet leather. While there are a number of problems which have been encountered in trying to develop such an aqueous system, the most common and perhaps the most obvious is the inherent re-wetting nature of the normal syntans and fatliquors employed in the basic treatment of the leather.
In general, syntans, retans and fatliquors have a very definite hydrophilic nature, and in the quantities employed to produce satisfactory leather this hydrophilic character is imparted to the leather itself. In order to obtain leather with the desired non-rewet characteristics, it was heretofore necessary to employ overly large amounts of water repellent chemicals.
More recently, an improved aqueous system was disclosed by Kelly and Papalos in the U.S. application Ser. No. 405,113 filed Oct. 10, 1973, now U.S. Pat. No. 3,934,975, issued Jan. 27, 1976, the specification and claims of which are incorporated herein by reference. Kelly and Papalos disclose the use of an alkylphenol-polyphenol condensate which has been alkoxylated and phosphated as the syntan. The treatement disclosed by Kelly and Papalos produced a leather having a water resistance comparable to that obtained using the most effective systems previously available, while producing a leather which was considerably superior to those produced from such previously available systems on a dry evaluation basis, and on an overall basis.